Question

What happens to sodium channels and potassium channels during repolarization of a neuron?

A. both potassium channels and sodium channels remain closed

B. the sodium channels close, followed by opening of the potassium channels

C. both sodium channels and potassium channels remain closed

D. the sodium channels open, but the potassium channels remain closed

E. both potassium channels and sodium channels remain open

The above repolarization of a neuron will result in which of the following ionic currents?

A. a potassium current will transport K⁺ ions out of the cytoplasm

B. a sodium current will transport Na⁺ ions out of the cytoplasm

C. a potassium current will transport K⁺ ions into the cytoplasm

D. a sodium current will transport Na⁺ ions into the cytoplasm

E. a sodium current will transport K⁺ ions into the cytoplasm

Answer 1

1) during depolarisation Na+ moves into the cell, and membrane potential increases, during repolarisation voltage-gated Na+ channel closes and voltage-gated K+ channel opens and K+ moves out of the cell, so membrane potential decreases, so the answer is

b)  the sodium channels close, followed by opening of the potassium channels

2) during depolarisation Na+ moves into the cell, and membrane potential increases, during repolarisation voltage-gated Na+ channel closes and voltage-gated K+ channel opens and K+ moves out of the cell, so membrane potential decreases, so the answer is

a)  a potassium current will transport K⁺ ions out of the cytoplasm